Casey Johnson's manner of death has been determined as "natural" by the L.A County Coroner's Office.
Casey's cause of death is listed as "diabetic ketoacidosis" -- which is a state of severe insulin deficiency.
As we first reported, Casey's body was found on January 4 ... but we're told her body was undiscovered for several days.
Casey Johnson Died of 'Natural' Causes
2/4/2010 2:00 PM PST BY TMZ STAFF
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